In the past various methods for producing data carriers of the abovementioned type have become known. For example multilayer data carriers are produced by connecting individual layers under the action of heat and pressure, which is generally referred to as the laminating technique. Elements to be incorporated in the card body can thereby be inserted in the layer structure in specially provided recesses before lamination. It has also been proposed to stamp single-layer card bodies out of a foil, whereby a recess can be simultaneously produced, e.g. for receiving an electronic module.
Finally it has become known e.g. from EP 0 277 854 B1 to manufacture data carriers with an embedded electronic module by injection molding. One provides an injection mold having a cavity whose dimensions correspond to those of the data carrier. Before injection of the plastic compound the electronic module is placed in the cavity on one half in such a way that the contact surfaces of the module lie flat against the half of the cavity and are fixed in this position by suction air. After that the plastic compound is injected via a lateral edge of the mold to form the card body so that the module is surrounded in form-fitting fashion by plastic compound. Suitable shaping of the casting compound of the electronic module causes the latter to be anchored reliably in the card body. The data carrier can now be removed from the mold.
To guarantee reliable fixation of the electronic module in the cavity during the injection process one can take additional measures. For example the module can be urged by a spring-mounted plate against the cavity half to which it is fixed which is lowered during injection of the plastic compound.
One obtains uniform and complete filling of the cavity with plastic material in injection molding by injecting the material into the cavity at very high pressure. This involves relatively elaborate apparatus since one must produce the high injection pressure, on the one hand, and apply high locking forces to the cavity to prevent its halves from "spreading apart" during the injection process, on the other hand. This makes injection molding tools quite expensive, so that injection molded articles in general and injection molded data carriers in particular can frequently be manufactured rationally only in high numbers.